超亲水工具微细电解加工技术研究

Electrochemical micromachining (EMM) plays an important role in the fabrication of metal complex microstructures with high qualifies. During EMM, the rapid transportation of electrolysis products in the machining gap is a key to acquire high machining accuracy because the gap between cathode and anode is usually only several micrometers even several sub micrometers. At present, both the machining accuracy and machining efficiency need be enhanced although many papers have been published about the improvement of the machining accuracy and machining efficiency during EMM. In this proposal, the micro electrode with a superhydrophilic surface is presented to prepare metal microstructures with high qualifies by enhancing the transportation of electrolysis products in the machining gap. Moreover，the wire's reciprocating vibration and the reciprocating motion of micro-spherical electrode in processing orientation are also presented to enhance the transportation of electrolysis products in the machining gap. The effect of the travelling rate of micro electrode with a superhydrophilic surface, and reciprocating motion of micro-spherical electrode with a superhydrophilic surface on the transportation of electrolysis products in the machining gap and machining gap width would be investigated in the theory and experiments. The key methods, such as the fabrication of micro electrode with a superhydrophilic surface, the integration of micro electrode and power generator with nano seconds pulse width, and the monitoring of micro electrochemical machining state, will also be done to provide a basis in the fabrication of metal microstructures with high qualifies preparing by EMM.

微细电解加工技术在高品质微尺度金属复杂结构的加工方面有着很大的发展潜力。微细电解加工中工具和工件间的加工间隙通常在微米/亚微米量级，因此加工产物的快速输运对于提高加工精度和加工效率极为重要。虽然国内外在此方面做了大量研究工作，但目前仍存在加工精度不够稳定、加工速度低等问题。本申请提出将具有超亲水表面的微细工具引入微细电解加工中，通过工具的“拉扯”带动更多的电解液运动，从而解决加工间隙内的产物快速排出难题。采用超亲水微尺度线电极的轴向往复运动促进微细电解切割加工时加工间隙内的产物快速排出，采用超亲水微球头工具的高速往复运动促进微细电解打孔时加工产物的快速输运。本项目将阐明强制对流情况下微细电解加工时微尺度间隙内加工产物的输运规律、微细电解加工的加工间隙分布规律和结构动态成形演变过程，突破微细工具电极制备、微细电极+纳秒脉宽脉冲电源的集成等关键技术，为实现高品质金属微细结构的电解加工奠定基础。

微细加工受到世界各国的高度关注，是当今世界最为活跃的科学研究领域之一，电解加工技术在微细制造领域有着很大的发展潜力，本项目聚焦于高品质金属微细结构的微细电解加工技术基础研究。.项目建立了线电极壁面速度滑移等效分析模型，揭示出在微细电解加工过程中，线电极表面粘附的氢气泡对壁面速度滑移具有很大的影响，气泡尺寸越大和/或气泡层内含气率越高会导致线电极壁面速度滑移增大。发现表面织构化线电极有助于促进氢气泡从线电极壁面脱附，减小壁面气泡层厚度及含气率，降低壁面速度滑移，增强微尺度加工间隙内的传质速度。通过理论分析和实验研究，归纳总结出间隙的分布规律。在金属钨丝表面加工出有序均匀分布的微织构，制备了具有不同表面亲水性的织构化微细线电极，有效提高了微细电解切割加工的加工效率、缝宽均匀性及表面质量。具有超亲水特性的表面织构化线电极的最大进给速度达到了0.5μm/s，是光滑线电极的2.5倍。.此外，还发现了微细电解切割加工时工具线电极表面吸附其它物质的现象，提出微小加工间隙内工具电极有时存在电泳沉积、金属电镀以及氢还原过程，这拓展了工具电极仅存在氢还原反应的原有观点。提出了双向脉冲电流微细电解线切割加工方法，有效抑制了工具电极表面产物吸附的问题，加工能持续稳定进行，在250μm厚的304不锈钢基体上制备长5.0mm微缝（断开电源停止加工）；采用传统加工方法，加工持续4.16小时后因短路终止，其微缝长1.8mm。.提出了气泡输运加工产物的微细电解线切割加工方法，有效地增强了微间隙内电解液的流动速度，提高了产物从加工区域排出的效率，可以显著抑制工具电极表面的电泳沉积和金属电镀现象。同时，该方法还保护已加工表面，显著改善了加工表面质量。加工出具有镜面效果的3J21、不锈钢材料微结构，连续加工路径长度51mm还可以稳定加工。